When I was in college, I accidentally wandered into the cafeteria kitchen with a classmate.

We found the chef actually using a mop to scrub the large pot, which was very unhygienic.
My classmate was very angry and immediately went to complain to the principal.
After listening to the criticism, the principal promised to resolve the issue immediately,
and came up with improvement measures to ensure food hygiene.
The next day, a large warning sign was placed in front of the kitchen door, which read:
Kitchen Area, No Unauthorized Personnel Allowed! Violators Will Be Severely Punished!